Menstrual cycle, trait estrogen level, and masculinity preferences in the human voice D.R. Feinberg a, * , B.C. Jones a,b , M.J. Law Smith a , F.R. Moore a , L.M. DeBruine a,b , R.E. Cornwell a , S.G. Hillier c , D.I. Perrett a a School of Psychology, University of St Andrews, St Andrews, Fife KY16 9JP, UK b School of Psychology, University of Aberdeen, AB24 2UB, UK c Royal Infirmary of Edinburgh, EH16 4SA, UK Received 25 May 2005; revised 5 July 2005; accepted 7 July 2005 Available online 1 August 2005 Abstract Men with low testosterone (feminine men) invest in relationships and offspring more than men with high testosterone (masculine men). Women’s attraction to testosterone dependent traits (e.g. masculine face shape) is enhanced during the late-follicular, fertile phase of the menstrual cycle. Attractive, feminine women have stronger preferences for masculine men as possible long-term partners than less attractive, masculine women. We manipulated 2 testosterone related vocal traits (voice pitch and apparent vocal-tract length) in voices to test if women prefer masculinized men’s voices to feminized men’s voices; masculinity preferences are enhanced at the fertile (late-follicular) menstrual cycle phase; the amount that masculinity preferences shift cyclically relates to average estrone-3-glucuronide concentration (the primary urinary metabolite of estrone, E3G). We found women displayed general masculinity preferences for men’s voices; masculinity preferences were greater in the fertile (late-follicular) phase of the cycle than the non-fertile (early-follicular and luteal) phase; and this effect was most pronounced for women with low average E3G concentration. As feminine women (i.e. those with high average E3G levels) are most able to obtain investment even from masculine men, these women may not need to change their mating preference or strategy during the menstrual cycle as much as masculine women. D 2005 Elsevier Inc. All rights reserved. Keywords: Vocal; Voice; Attractiveness; Masculinity; Dominance; Pitch; Vocal-tract; Estrogen Introduction Masculine traits in men indicate long-term health (Rhodes et al., 2003), higher reproductive success (Mueller and Mazur, 1997, 1998; Pawlowski et al., 2000), but reduced commitment to relationships and offspring (Burn- ham et al., 2003; Gray, 2003; Gray et al., 2002, 2004). By contrast, feminine traits in men indicate a higher probability of relationship commitment and paternal investment (Burn- ham et al., 2003; Gray, 2003; Gray et al., 2002, 2004). Women exhibit stronger facial masculinity preferences during the most fertile phase of the menstrual cycle (late- follicular phase) than at other times (Johnston et al., 2001; Penton-Voak and Perrett, 2000; Penton-Voak et al., 1999). Menstrual cycle shifts in facial masculinity preferences have been observed when women evaluated men’s faces for short-term relationships (Penton-Voak et al., 1999) and when relationship context was not specified (Johnston et al., 2001; Penton-Voak and Perrett, 2000; Penton-Voak et al., 1999). Masculinity in men’s face shape is preferred by women more for short-term than long-term relationships (Johnston et al., 2001; Little et al., 2002; Penton-Voak et al., 1999, 2003). Preferences for male facial masculinity are influ- enced by the attractiveness and femininity of the female judges (Little et al., 2001; Penton-Voak et al., 2003). While relatively unattractive and masculine women demonstrated stronger preferences for masculine males as short-term 0018-506X/$ - see front matter D 2005 Elsevier Inc. All rights reserved. doi:10.1016/j.yhbeh.2005.07.004 * Corresponding author. Fax: +44 1334 46 3042. E-mail address: drf3@st-andrews.ac.uk (D.R. Feinberg). Hormones and Behavior 49 (2006) 215 – 222 www.elsevier.com/locate/yhbeh